Industrial automation control systems comprise an industrial controller, which is a special purpose computer used for controlling industrial processes and manufacturing equipment on a real-time basis. Under the direction of a stored program, the industrial controller examines a set of inputs reflecting the status of the controlled or another machine or process and changes a set of outputs directed to the controlled machine or process. The inputs and outputs may be binary or analog.
Industrial controllers differ from conventional computers in that their hardware configurations vary significantly from application to application reflecting their wide range of uses. This variability is accommodated by constructing the industrial controller on a modular basis having removable input/output (I/O) modules that may accommodate different types and numbers of input and output points depending on the process being controlled. Also, the need to connect the I/O modules to different pieces of machinery that may be spatially separated from each other and located remotely from the controller has led to the development of distributed I/O systems that take a variety of forms. In one example, a self-contained discrete or “block” I/O module contained in a single housing is “distributed” and located remotely from the industrial controller so as to be located near the machine or process being controlled, e.g. directly mounted on or adjacent the machine or process being controlled. The block I/O module contains digital and/or analog input and/or output (I/O) circuits that provide input and/or output to the machine or process being controlled, a built-in power supply that receives electrical power and provides operative power for the I/O module itself and, optionally, any sensors or other field devices connected thereto, and a built-in network communications adapter for communicating with the industrial controller over a wired or wireless network. In another distributed I/O example, a single network adapter is connected to multiple self-contained I/O modules through a backplane circuit, in which case the number and type of I/O modules can be varied as needed, but the type and number of input and output points of each I/O module, itself, cannot be altered after the module is manufactured. FIG. 1 shows an example of an industrial automation control system S comprising an industrial controller 100 such as a programmable logic controller (PLC) or the like for controlling an industrial process or machine 126 (generally referred to as the controlled system 126). The controlled system 126 may comprise one or more field devices FD such as sensors, switches, safety devices, or the like connected thereto or otherwise associated therewith. A distributed block I/O module B′ is located remotely from and connected to the industrial controller 100 through a wired or wireless network 116, which is typically a high-speed serial network implementing a suitable industrial automation network protocol such as ControlNet, DeviceNet, EtherNet/IP, RIO, ASi, PROFIBUS, PROFINET, Foundation Fieldbus or any other suitable industrial automation network protocol(s).
As noted above, the block I/O module B′ is self-contained in a single housing H′ and comprises a network adapter 112′ providing a connection 114′ to the network 116 via network connector(s) 112c′. The network adapter 112′ communicates over the network 116 with the industrial controller 100 to receive output data from the industrial controller and to provide input data from the controlled system 126 to the industrial controller 100 for processing according to a stored control program.
The block I/O module B′ also comprises one or more I/O circuits 120′ that are permanently installed in the housing H′ and that connect via field connections 124′ (e.g., electrical cables, fiber optic cables, a wireless connection, etc.) with the field devices FD or other parts of the controlled system 126. In the case of hard-wired field connections 124′, the cables thereof connect to the I/O circuit(s) 120′ via I/O connectors 124c′ which are typically M8, M12, or other industry standard field connectors. As is understood in the art, the I/O circuit(s) 120′ convert digital data received from the controller 100 via network adapter 112′ into output signals (either digital or analog) in a form suitable for input to the controlled system 126. The I/O circuit(s) 120′ typically also receive digital or analog signals from the controlled system 126 and convert it to digital data suitable for transmission to the controller 100 through the network adapter 112′. In particular, each I/O circuit 120′ comprises electronic circuitry such as A/D converters, D/A converters, multiplexers, buffers, counters, controllers, serializers, timers, I/O logic, memory, and/or like electronic devices such that the I/O circuit 120′: (i) connects via field connections 124′ with the controlled system 126; (ii) converts digital data received from the industrial controller 100 via network adapter 112′ into analog or digital output signals for input to the field devices FD or other parts of the controlled system 126; and/or, (iii) receives digital or analog signals from the controlled system 126 or elsewhere and converts the received signals to digital data suitable for transmission to the industrial controller 100 via network adapter 112′. The block I/O module B′ further comprises a power supply PS′ that is connected through a power connector PC′ to an external electrical power source PWR that supplies electrical voltage V to power the module B′ and, optionally, to power sensors or other field devices FD connected to the module B′ via field connections or cables 124′.
Block I/O modules B′ as described above provide many advantages, but a primary disadvantage is that they cannot be easily customized or altered for a particular machine or process being controlled. In some cases, two or more different block I/O modules B′ must be deployed, each having different configurations, but where neither module is used to its full capacity and each module includes unused I/O connection points. In other cases, modifications to the controlled system 126 will necessitate installation of a new block I/O module B′, when it would be preferable to simply reconfigure the existing block I/O module B′ with minimum disconnection of network connections 112c′, power connections PC′, and field connections 124c′ to minimize machine down-time, labor costs, and the opportunity for wiring errors upon reconnection. Similar drawbacks exist for I/O modules other than block I/O modules, such as chassis-based I/O modules, and cabinet-based distributed I/O modules, and the like.
Also, as shown in FIG. 1A, with known block I/O modules B′, the power connector PC′, the network connector(s) 112c′, and the I/O connectors 124c′ are all located on the front face FF′ of the module B′ such that the connection axis CX′ for mating these connectors with their respective cables C extends perpendicular to the mounting surface R on which the module B′ is mounted with a rear face RF′ of the module B′ abutted with the mounting surface R. This leads to an undesirable situation in which the front face of the module is very crowded with connectors and cables, which limits space for indicator lights or other indicia and can complicate wiring or re-wiring operations in the field and lead to errors. Known arrangements also undesirably increase the amount of open space required adjacent the front face FF of the module to accommodate the multiple cables C and to provide each cable C with sufficient space to include a desired bend radius as required to prevent damage to the wires.